This ZATCA Guideline (Version 2, May 2023) explains Electronic Invoicing in the Kingdom of Saudi Arabia, reading the E-Invoicing Regulation together with the VAT Law, its Implementing Regulation and the E-Invoicing Resolution. It clarifies key definitions, the Persons covered by Article 3 of that Regulation, and the differences between Tax Invoices, Simplified Tax Invoices and Electronic Notes. It sets out Generation Phase requirements from 4 December 2021 and Integration Phase requirements from 1 January 2023, covering clearance, reporting of Simplified Tax Invoices to the FATOORA Portal within 24 hours, prohibited functions, taxpayer obligations, advance payments, ZATCA onboarding, failure scenarios, QR code validation and FAQs.